.layout{
    width: 960px;
    margin: auto;
}

.banner{
    position: relative;
    overflow: hidden;
    width: 600px;
    height: 200px;
    border-radius: 10px;
    border: 2px solid black;
}

.banner_img li{
    float: left;
    list-style-type: none;
}

